—90— 
be mistaken for some of the foliaceous lichens but the Hepatics are always 
much greener and produce spores in a very different manner. 
In the leafy-stemmed Hepatics, often called Scale Mosses, the leaves are 
without midrib and are nearly always in two ranks and flattened so as to lie 
in one plane, but in the great majority of cases there is a third rudimentary 
row on the inner side which are called underleaves, or amphigastra by those 
devoted to technical names. The pedicel which corresponds to the seta of 
the mosses does not, as a rule, grow much until the spores are nearly ripe, 
when it elongates very rapidly. The pedicels and capsules are of a much 
more delicate structure than in the mosses so that they disappear soon after 
the spores have escaped, but the peculiar and characteristic scales or bracts 
around the base of the pedical often remain much longer and help greatly in 
identifying species. Immediately surrounding the base of the pedicel is a 
tubular, somewhat three-sided organ called the inner involucre or perianth, 
surrounding this the outer involucre, called simply involucre by many 
authors. This latter maybe either tubular or composed of separate leaf-like 
divisions of varied shapes, called involucral leaves or bracts, or perichatial 
leaves or bracts, or simply bracts. Either one, or even both, of these invo- 
lucres may be lacking in some species. 
So far as possible gametophyte characters have been used in the keys 
and descriptions and in the great majority of cases identification is easy from 
this part of the plant alone. Hepatics generally grow in moist situations on 
soil, roots of trees, and decaying wood. 
Key to Families. 
Plants leafy, mosslike in appearence except for the two-ranked leaves 
entirely lacking midrib Scale Mosses (Jungermanniacese) . 
Plants consisting of a flattened green thallus, sometimes nearly circular but 
usually elongated and branching. (See illustrations of Riccia, Mar- 
chantia, Anthoceros, etc.) A. 
A. 
1. Capsules, if present, immersed in the tissue of the plant. Plants float- 
ing on the surface of still water or floating on the mud along the 
banks Riccia. 
Capsules raised well above the thallus. Plants often growing in mud but 
never floating 2 - 
2. Stomata (in our genera) present, easily discernable with a lens as small 
pores on the upper surface of the rather thick thallus ; capsule borne on 
a special stalked receptacle as in Marchantia. 
Liverworts (Marchantiacese). 
Stomata not present, on. the thinner thallus: capsules never borne on a 
special stalked receptacle 3- 
3. Capsules very long and slender, splitting into two valves when ripe after 
the manner of a mustard pod, the slender hairlike columella remaining 
in the center. Horned Liverworts (Anthocerotaceae). 
Capsules globular or ovoid, splitting into four valves; columella lacking. 
Thalloid Scale Mosses (Metzgeriaceae). 
